1. Field
Aspects relate to a device for the application of bone substitute material especially for use in the dental, orthopedic or esthetic field, comprising a cylinder.
2. Discussion of Related Art
In dentistry, bone substitute material is used, in part, in order to fill larger cavities after extractions or resections. Thus, an interpenetration of the cavity with soft tissue is prevented and the build-up of bone is accelerated, because bone is necessary to form a stable base for teeth, implants and prostheses. This bone substitute material is extremely costly and, accordingly, one aim of the present disclosure is to minimize material loss during application.
The granulate bone substitute material is designed to be mixed with a liquid phase. That liquid phase may be e.g. the patient's own blood or a physiological saline solution. The granulate bone substitute material may be any of the numerous materials and compositions of synthetic or natural origin that are known to stimulate bone formation, bone regeneration, bone repair, bone remodeling and/or bone replacement. An example of a suitable bone replacement of natural origin is Geistlich Bio-Oss®, commercially available from Geistlich Pharma AG, which is manufactured from natural bone by a process described in U.S. Pat. No. 5,167,961. An example of a suitable bone replacement of synthetic origin is a granulate of the biphasic calcium phosphate/hydroxyapatite material described in international application PCT/EP2010/003590.
Conventionally, the supplied granulate is prepared in a container and a liquid phase is added, after which the product, which is present in granulate form, is wetted. Care is to be taken here that the liquid phase is in a correct ratio, so that the wetted material has a pasty consistency. In the case where a certain excess of the liquid phase is present, the latter should be drained by means of a sieve. This handling is time-consuming, must be carried out carefully and accordingly this is done by the practitioner who is carrying out the treatment. Once the mixture is prepared, it must be drawn up by means of a syringe consisting of a cylinder and piston rod with a correspondingly sealing piston, or by using a surgical scoop to implant the product in the patient. If the material is relatively fluid, then it can indeed be taken up well, but when the prepared material has to be applied in the upper jaw, then the loss of material is relatively high. If, however, the material is more firm in consistency, then drawing the material into the syringe can be difficult even though material loss is minimized.
Devices have been known since the 1980s, in which the mineral component is stored in a cylinder of a first application syringe, and then by means of a second injection syringe, which is able to be coupled with the first, the collagen phase, i.e. the liquid phase, is added to the mineral component. For a corresponding thorough mixing, the two injection syringes, which are coupled with each other, can be moved so that the mixture is able to be moved from one syringe into the other syringe. For this solution to function at all, however, the entire mixture must be relatively fluid. Such a two-syringe device is described for example in EP-A-0266058.
As already mentioned, it may be beneficial when the material has a high viscosity, but the material then will tend clog when it pressed through a constriction. This problem has already been recognized and accordingly, for example, document US 2006/0264964 shows in FIG. 5 a solution in which the material is discharged via a discharge nozzle, wherein this discharge nozzle has the same internal diameter as the tube on which it is fastened. Reference is to be made in particular to FIGS. 5 and 7 in this respect. This publication clearly shows that by means of the piston cylinder unit the material can be pushed forward out from the cylinder only up to the discharge nozzle, the bone substitute material remaining in the discharge nozzle being therefore lost.
Document US-B-7118378 teaches another solution which is designed especially for dental applications and accordingly realizes the supply via a curved discharge nozzle. Here, the entire cylinder is embodied in a curved version. Accordingly, the piston rod must be elastically deformable. Such a solution is not without problems, notably because such cylinders cannot be manufactured by injection molding techniques, and therefore must be manufactured from a thermoplastic tube which is subsequently bent. This leads to practically uncontrollable alterations in the cross-section in the bending region. Accordingly, such a device tends to become jammed. Instead of a piston, two sealing rings are now pushed onto the thinned end of the piston rod, which are intended to undertake this function. As a mixing is to be carried out here in the cylinder and one is aware of the problem of the blocking of the material, the discharge nozzle itself has been embodied so as to be running in a straight line, and the material is only mixed in this region. Therefore, the piston per se is to be regarded as a rigid element and accordingly this piston does not act in the curvature region. However, this also means that the actual curvature scarcely comes to lie in the patient's mouth, but rather outside the pharynx. The desired advantage, namely of feeding the relatively highly viscous material directly in the region of the application in a curved path, hence cannot be achieved with this prior art device.
Document WO-A-2008/153513 discloses a syringe-type delivery device for the application of bone graft material comprising a cylinder, in which the ready-mixed bone substitute material is situated, with an end on the holding side and an end on the discharge side, wherein a piston rod is situated in the cylinder, on which piston rod a sealing piston is placed. A removable attachment with a straight or curved cannula for discharging the bone substitute material engages via a threaded adapter with an external thread on the discharge side end of the cylinder.
Similarly, document WO-A-2006/125100 discloses a graft syringe assembly for the provision of bone graft material to anatomical structures. The assembly has a syringe barrel including external threads on its distal end which are adapted for engaging the inner threads of a syringe adapter. In order to offer flexibility with the delivery point of bone graft material, a flexible delivery tube is attached to the syringe adapter by a luer fitting. In order to mix the bone graft material and other fluids in the device, fluid may be introduced by a needle or another device through an opening in the syringe adapter or through an alternative site port provided on the syringe barrel.
Document US-A-2003/0069545 shows also a similar graft delivery syringe which can mix and dispense solid bone substitute and fluid additives for the implantation of bone replacement materials. The syringe comprises a cylindrical syringe barrel and a piston connected to a rubber plunger. To introduce fluids into the inner cavity defined by the syringe barrel, the rubber plunger includes an X-shaped opening, which also allows air and excess fluid to escape from the barrel.